[ussuri][goal] Drop python 2.7 support and testing

OpenStack is dropping the py2.7 support in ussuri cycle.

Complete discussion & schedule can be found in
- http://lists.openstack.org/pipermail/openstack-discuss/2019-October/010142.html
- https://etherpad.openstack.org/p/drop-python2-support

Ussuri Communtiy-wide goal:
https://governance.openstack.org/tc/goals/selected/ussuri/drop-py27.html

Change-Id: Iadbea735f22cd8456a32f10fda598dc6a2983ec7

.zuul.yaml

@@ -47,5 +47,4 @@
       - openstackclient-plugin-jobs
       - build-openstack-docs-pti
       - check-requirements
-      - openstack-python-jobs
-      - openstack-python3-train-jobs
+      - openstack-python3-ussuri-jobs

doc/requirements.txt

@@ -3,6 +3,5 @@
 # process, which may cause wedges in the gate later.
 
 # this is required for the docs
-sphinx!=1.6.6,!=1.6.7,>=1.6.5,<2.0.0;python_version=='2.7' # BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.5;python_version>='3.4' # BSD
+sphinx!=1.6.6,!=1.6.7,>=1.6.5 # BSD
 openstackdocstheme>=1.23.2 # Apache-2.0

requirements.txt

@@ -2,8 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
-networkx>=2.2,<2.3;python_version<'3.0'  # BSD
-networkx>=2.3;python_version>='3.4'  # BSD
+networkx>=2.3 # BSD
 aodhclient>=0.9.0 # Apache-2.0
 gnocchiclient>=3.3.1 # Apache-2.0
 python-barbicanclient>=4.5.2 # Apache-2.0

setup.cfg

@@ -6,6 +6,7 @@ description-file =
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/python-openstackclient/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,8 +14,8 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3 :: Only
+    Programming Language :: Python :: Implementation :: CPython

setup.py

@@ -16,14 +16,6 @@
 # THIS FILE IS MANAGED BY THE GLOBAL REQUIREMENTS REPO - DO NOT EDIT
 import setuptools
 
-# In python < 2.7.4, a lazy loading of package `pbr` will break
-# setuptools if some other modules registered functions in `atexit`.
-# solution from: http://bugs.python.org/issue15881#msg170215
-try:
-    import multiprocessing  # noqa
-except ImportError:
-    pass
-
 setuptools.setup(
     setup_requires=['pbr>=2.0.0'],
     pbr=True)

tox.ini

@@ -1,23 +1,22 @@
 [tox]
-minversion = 3.1.1
-envlist = py27,py37,pep8,docs
+minversion = 3.1.0
+envlist = py37,pep8,docs
+ignore_basepython_conflict = true
 
 [testenv]
+basepython = python3
 deps = -r{toxinidir}/test-requirements.txt
 commands = stestr run --slowest {posargs}
 
 [testenv:pep8]
-basepython = python3
 deps=-r{toxinidir}/test-requirements.txt
 commands =
   flake8
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:docs]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands = 
   sphinx-build -a -E -W -d doc/build/doctrees -b html doc/source doc/build/html